Method of assembling rubber filaments into thread



June 4, 1940. R 5 JAMES 2,203,387

METHOD OF ASSEMBLING RUBBER FILAMENTS INTO THREAD Filed July 19, 1938 F I M f/ INVENTORQ A OBE/r7 6145c??? Lil/WES.

Patented June 4, 1940 UNITED STATES PATENT OFFICE METHOD OF ASSEIVIBLING' RUBBER FILAMENTS INTO THREAD company Application July 19, 1938, Serial No. 219,956 In Great-Britain September 9, 1937 16 Claims.

My invention relates to a rubber thread comprising three or more filaments arranged in a non-planar formation, or grouped about a center in a unitary structure, and to a method of making such threads, and relates more particularly to thread of the above type having means to limit its extensibility or stretching to a predetermined limit and thus to control the stretch of the thread.

In my present invention three or more filaments are arranged around a core thread having a limited extensibility and are joined by adhesion to each other so as to form a unitary structure. The rubber threads thus joined are preferably formed. by extruding an aqueous dispersion of rubber, such as a compounded latex, into a bath such as a coagulating bath which sets the extruded dispersion to a thread-like filament. A number of rubber threads thus freshly formed may be assembled about the core thread and, when freshly formed and wet, may have sufficient adhesiveness to join in a unitary structure about the core thread or, if the individual rubber filaments do not have sufficient adhesiveness to adhere to each other in a unitary structure, their adhesiveness may be enhanced or made sufiicient by an adhesive solution applied to their surfaces.

The rubber filaments or threads may be associated about the central thread by any suitable manner or means. For example, any desired number of the rubber threads may beassociated by mechanically arranging them as they leave a coagulant bath into which they have been extruded as latex. This may be accomplished, for example, by feeding the filaments and core thread to a uniting or ganging roller. The arranging and contacting of the desired number of filaments and core thread can be carried out in stages. For example, two filaments may be allowed to double in a channel of the'coagulant bath and the double filament thread may then be combined witha single filament and a core 45 thread of suitable relative thickness so as to produce a three-filamentthiead and in which'any one filament is in contact with the other two. The rubber filaments or threads may be arranged in any desired manner as, for example, into a trefoil thread by forming two threads into a double filament in a liquid coagulant and a single filament in a liquid coagulant bath positioned above the two-filament bath, and combining the double filament thread with a core and then passing the double filament thread, the

core thread and single filament into a uniting or gauging roller in such a manner that the single filament thread falls on top of the double filament thread onto which the core thread has been laid,

with the result that the three filaments surround the core thread, forming a unitary, multi-filament structure.

A preferred embodiment of the present invention consists in applying and suitably modifying the method described in my co-pending application Serial No. 206,998, filed May 10, 1938, so as to incorporate a core thread in an assembly of three or more rubber threads. In the said copending application three or more rubber thread threads, extruding nozzles are arranged'equi distantly, as in a triangular formation, supplied with an aqueous dispersion of rubber, such as a latex mixing, so as to force a small stream from each nozzle into the coagulant. The rising coagulated filaments are then drawn through the upper surface of the coagulant or setting bath, which draws them into a most compact arrangement by surface tension effects. The rubber structure thus formed may be continuously drawn over a roller, the direction at which the threads 5 leave the bath being approximately vertical, or sufficiently near vertical, as to maintain substantially uniform surface tensions about the assembly.

As a result of this assembling of the rubber threads their circular section may be distorted. For example, a trefoil thread produced according to the method of the invention generally has a solid-centered triangular cross section, and quatre-foil thread has usually a solid-centered cruciform cross section. If, in these cases, the center is not filled, the size of the hole is influenced by the diameter of the individual filaments, their degree of coagulation and their distortability. If five or six filaments are associated according to this. method, the filaments group themselves into circular formation, leaving a hollow center-producing, in effect, a tubular multi-filament thread.

According to the preferred embodiment of my present invention, therefore, the method for the production of rubber thread comprising three or more and, preferably, five or six filaments integrally united and arranged in a compact group about a core center of limited extensibility and without twisting or braiding, comprises extruding a number of latex filaments at a common speed into a liquid coagulant, or the like, leading a number of core threads vertically through the coagulant and drawing a core thread and a group of three or more, preferably five or six, of the coagulated filaments vertically out of the coagulant in such a way that the wet filaments contact with each other into a unitary structure around the core thread.

It is to be understood. that in all of the embodiments of the invention there must be a suitable relationship between diameter of the core thread and the diameter and number of the rubber filaments.

The core thread may consist, for example, of a. destructible textile thread such as one of cellulose acetate. Such a core thread, being inextensible, produces in the article of my invention a multi-filament thread having no stretch at all. If a multi-filament thread capable of stretching within controllable limits is desired, a. core thread is used having a definite degree of elongation. For example, if a fiber covered thread, for instance a rubber yarn of 200% elongation, is used a multi-filament thread of 200% elongation is obtained. A core of material destructible by certain solvents, for example, a cellulose acetate thread, wrapped with a textile thread not destructable by such solvents as, for example, a cotton thread or filament, can also be used. On dissolving away the soluble material, for instance, cellulose acetate, by means of a suitable solvent such as acetone, a multi-filarnent thread is left having a coiled cotton filament, and the multifilament thread thus obtained will stretch to the point where the cotton coils disappear and the cotton thread becomes taut. By varying the number of cotton coils per inch of destructible filament, the controlled stretch of the multifilament thread produced according to the invention can be altered as desired.

In the above the term latex has been used to designate broadly an aqueous dispersion of, or containing, rubber, gutta percha, balata or similar vegetable resins occurring naturally, or artificially obtained. Artificial aqueous dispersions may include those of coagulated rubber, vulcanized rubber, synthetic rubber, waste or reclaim. Aqueous dispersions of vulcanized latices can also be employed, or various admixtures of the above aqueous dispersions and latices can be used. Any of such dispersions; may contain the usual known compounding ingredients and, either with or without the compounding ingredients, may be in concentrated form. Concentrates such as are obtained in British Patents 290,313 and 219,635, or United States Patent 1,846,164, to which may be added any one or more of the usual compounding ingredients, may also be used. The aqueous dispersions may be made heat sensitive by methods well known in the art. The words aqueous dispersions and latex are used herein to designate generically the above and similar types of materials.

The term coagulant is used to designate broadly liquid media which bring about the solidification of aqueous dispersions of rubber, or latex, by coagulation, gelling, or by dehydration and coagulation.

The various features of the invention are i1- lustrated diagrammatically and solely by way of example in the accompanying drawing, in which-- I Fig. 1 is a diagrammatic vertical section through a bath in which the rubber threads formed by coagulation are laid mechanically in selected formation about a core thread.

Figs. 2, 3 and 4 are vertical cross sections on .the lines 2--2, 3-3 and 44 of Fig. 1.

Fig. 5 is a View similar to that of Fig. 1 showing the manner in which a number of rubber threads,

three being shown by way of example, are mechanically laid or ganged on a roller.

Fig. 6 is a vertical section illustrating the perferred manner of forming the rubber threads about the core thread, and

Fig. 7 is a longitudinal sectional View showing a core of limited extensibility in the form of a helical thread enclosed within a rubber filament structure, 7 1

In the modification of the invention shown in Figs. 1, 2,3 and 4, a pair of rubber threads l and H are drawn in close association on the surface of a liquid l2 as, for example, the surface of a coagulating bath. The freshly formed rubber threads will tend to adhere at their point of contact. As the threads l0 and H pass over the surface of the bath l2, a core thread I3 is supplied over a roller M in position to fall into the trough between the rubber threads l0 and H as shown in Fig. 3. Thereafter, a third rubber thread i is passed over a roller l6 so as to fall onto the rubber threads 10 and H and cover the core thread as shown in Fig. 4. If the rubber threads Ill, H and I5 have been freshly formed and are still wet they will adhere to form a unitary structure.

In the modification shown in Fig. 5 the rubber threads Ill and II are drawn upwardly from the coagulating bath 12 over a ganging roller I"! while the core thread I3 is fed into the notchbetween the threads as shown in Fig. 3, and thereafter the covering rubber thread I5 is drawn into position above the notch as shown in Fig. 4.

In the third embodiment of the invention shown in Fig. 6, an aqueous dispersion, such as a compounded latex, is supplied through an inlet pipe l8 into an extruding head I9 containing a number of nozzles, three being shown by way of example. Through these nozzles three separate streams of latex are extruded directly into a coagulating bath where they are immediately set to filaments or threads 2|, 22 and 23, and rise upwardly. After leaving the surface of the bath they pass upwardly in a vertical direction over a roller 24. Simultaneously with the extrusion there is drawn upwardly through the bath and over the roller 24 a central core thread 25. As the threads 2!, 22 and 23 assemble and are drawn into a close formation by the surface tension at the surface of the bath, they enclose the core thread 25 in a structure such as shown in Fig. 4.

In Fig. 7 there is shown on an enlarged scale a thread structure havinga core formed by a helical thread 26 of inextensible material en" closed in a structure formed by contacting rubber ,filaments 21 and 28, the structure being otherwise the same as shown in the previous figures.

It will be understood that the above examples are given merely by way of illustration and that a number of other methods of assembling rubber threads about a core threadmay be used and that, of course, any number of threads may be employed to produce any desired structure.

What I claim is:

1. A rubber thread which comprises a central core and a plurality of rubber filaments about said core and joined each to adjacent filaments to form an enclosure for said core; said core having less extensibility than said rubber filaments.

2. A composite thread of limited extensibility which comprises a central core thread having a non-stretchable filament arranged helically and a plurality of rubber filaments in tangential contact with each other about said core thread to form an enclosure therefor.

3.'A composite thread structure of limited extensibility which comprises a central core thread and a plurality of rubber filaments assembled symmetrically about said core thread, each said rubber filament contacting with the adjacent filaments on each side to form a complete enclosure about the core, said core having less extensibility than said rubber filaments.

4. The thread assembly of claim 3 in which the inner faces of said rubber filaments are distorted by contact with said core, said core having less extensibility than said rubber filaments.

5. A method of forming a rubber thread structure of limited extensibility which comprises forming rubber filaments from an aqueous dispersion of rubber composition and drawing a plurality of said filaments into a hollow assembly about a central core of non-stretchable filament in helical form.

v 6. The method of claim 5 in which said rubber filaments are assembled while freshly formed and while they have adhesive surfaces.

7. The method of forming a rubber thread structure of limited extensibility which comprises extruding an aqueous dispersion of rubber composition into a coagulant to form freshly coagulated filaments, drawing a core element of limited extensibility through said coagulant and drawing freshly coagulated filaments into a symmetrical arrangement about said central core element.

8. A method of forming a composite rubber thread of limited stretchability which comprises forming a core of two different filaments, one of which is destructible under certain conditions, and the other of which is not, said elements being twisted together to form said non-destructible filament into a helical formation, drawing said core structure upwardly through a coagulating bath, extruding a number of rubber filaments from an aqueousdispersion of rubber composition about said core and drawing said core and filaments upwardly through the surface of said coagulant;

9. A method of forming a composite rubber thread of limited stretchability which comprises forming a core of two different filaments, one of which is destructible under certain conditions, and the other of which is not, said elements being twisted together to form said non-destructible filament into a helical formation, drawing said core structure upwardly through a coagulating bath, extruding a number of rubber filaments from an aqueous dispersion of rubber composition about said core, drawing said core and filaments upwardly through the surface of said coagulant and thereafter dissolving the destructible filament of said core.

10. A rubber thread which comprises a plurality of filaments of rubber composition each joined to the adjacent filaments to form a hollow enclosure, and a core Within said enclosure of difierent extensibility from that of said filaments.

11. A method of forming a rubber thread structure of limited extensibility which comprises forming filaments from an aqueous dispersion of rubber composition, and continuously placing said freshly formed filaments about a core of material of less extensibility than that of said rubber composition to form a complete enclosure for said core while said freshly formed filaments of rubber composition have suflicient surface adhesiveness to cohere at their contacting surfaces.

12. The method of claim 11 in which said filaments of rubber composition are brought into position about said core in a liquid medium.

13. The method of claim 11 in which said rubber filaments are brought into position about said core substantially simultaneously.

14. The method of claim 11 in which said filaments of rubber composition are brought successively into position about said core.

15. A method for the production of a composite thread structure of limited stretchability which comprises positioning symmetrically on an assembly of two contacting rubber filaments, a core thread of less extensibility than that of said filaments and laying a third rubber filament on said assembly to cover said core and enclose it in said rubber filaments while the surfaces of said filaments are sufliciently adhesive to form a coherent structure. 7

16. A method of forming a trefoil rubber filament assembly on a central core of limited stretchability which comprises extruding an aqueous dispersion of rubber composition into a coagulant in a pair of streams to forma pair of filaments, and bringing said filaments into contact side by side and drawing said assembled pair of filaments on the surface of said coagulant, laying a core of material of less extensibility from that of said filaments immediately above their lines of contact and extruding a third rubber filament from an aqueous dispersion of rubber composition and laying it on said assembled pair of filaments and core to cover said core and contact with the filaments of said double filament assembly while the surfaces of said filaments are sufiiciently adhesive to form a coherent structure.

ROBERT GILBERT JAMES, 

